Mobile Discrepancancies FAQ s - IAB UK

Mobile Discrepancancies FAQ s - IAB UK

Mobile Discrepancancies




Section One - Discrepancies

What are the top reasons for discrepancies? 2

What are the basic checks I should be doing to reduce discrepancies? 3

How can different mobile ad servers, affect third party ad serving? 3

Can you use third party ad-serve for HTML 5 ad units? 4

Is there a difference between rich media and standard ad serving on mobile? 4

What is the difference between an install and a download? 4

Section Two - Connection

Why are IP addresses not as reliable on mobile? 5

What happens when a user doesn’t have a data connection? 5

How is location determined on a mobile device? 6

Section Three - Tracking

Do you need mobile specific tags for tracking? 7

What are the differences between app and browser ecosystems for tracking? 7

What targeting mechanisms can be used across mobile apps? 7

Do cookies demonstrate the same behaviour on mobile browsing as they do on

desktops? 8

If you are using fingerprinting and other mechanisms to deliver relevant

advertising, what privacy concerns should you be aware of? 9

Are there any mechanisms to detect fraudulent clicks? 9

Glossary 10


The mobile discrepancies FAQ document is a result of the complex nature of ad

serving on mobile. This booklet is aimed at people involved with the ad serving

process, but not necessarily on the technical side of things, to understand better

why discrepancies occur and how they can be reduced. We have worked with

eighteen different companies, allowing the responses to cover as much of the

marketplace as possible. However, this also means that some of the content

may not be relevant to your business model and this should be considered when

referencing the booklet. If you would like more information about how the

booklet was collated please contact Mike Reynolds (

The booklet covers three main areas, Discrepancies, Connection, and Tracking.

It aims to answer some of the questions which are the cause of confusion where

discrepancies are concerned. This document focuses on impressions, which

is defined as a measure of the number of times an ad is displayed, whether

it is clicked on or not. Each time an ad displays, in theory, it is counted as one



Section One - Discrepancies

What are the top reasons for discrepancies?

• Connection – A mobile device does not have a fixed connection and therefore

connectivity is sometimes lost. When a mobile goes out of network range as a

page is being loaded, and ad served, the ad server registers an impression but

the tracker / site does not.

• Tags – If third party tags are not certified with first party ad servers, or are not

compatible with the publishers SDK’s (Software Development Kits), then

discrepancies will occur.

• Time zone differences – Different vendors may provide reports in different

time zones. This is especially problematic with short campaigns e.g. a campaign

that runs over one day. To avoid this problem, prior to the campaign going live,

you should always ask what time zone the report is being pulled in. As well as

asking if the vendor can easily provide report break down hour by hour. It is also

good practice to verify that the ad server time is the same as the reporting time.

• Counting – The way in which impressions are counted can cause large

discrepancies. In most cases server side tracking count impressions when a

beacon is sent to the servers to request the creative, whilst client side tracking

count impressions when a creative is retrieved and rendered.

• Terminology – It’s always important to be talking the same language before

a campaign goes live. Making sure all parties are defining metrics in the same

way will ensure the consistency of reporting, which will reduce the likelihood of

discrepancies occurring. For impressions, there are a number of ways they can

be counted by the different parties involved e.g. Impression on ad call vs. server

call vs. delivered vs. viewable vs. viewed, and therefore it’s important to define

this prior to launching the campaign.


What are the basic checks I should be doing to reduce discrepancies?

• Testing before the campaign goes live. Comprehensive pre-launch testing,

in conjunction with all tracking partners, to check for discrepancies before the

campaign goes live. Where possible, checks should be performed across a

range of different mobile devices, and mobile ad formats, that represent the

current mobile landscape.

• You should be checking if the advertisers third party tags are compatible

with the publishers / ad networks / real time bidding (RTB) platform server.

• Use trusted ad servers. Some ad servers offer new tag types which are

better suited to the mobile eco-system, and should therefore be implemented

where possible.

• Tagging correctly. Make sure the tags are implemented correctly and replaced

with the correct cache buster for the ad server they are being served


• Check time zone of reports. Establish what time zones are being used for


• Use creative guidelines. Ensure that you are using the IAB US and MMA’s

Mobile Phone Creative Guidelines’ which establish detailed specifications for

mobile phone ad units. It is also recommended to use the IAB US’s MRAID for

mobile rich media ads running in mobile apps.

• Communication between all parties. Make sure that metrics are being

defined the same by all parties involved, and therefore reporting is accurate.

How can different mobile ad servers, at supplier side, affect third party

ad serving?

• Second and Third party ad servers will have different algorithms, tracking

definitions, and methodologies for counting both impressions and clicks.

• First party ad servers may not have the same methodology for counting

impressions as second and third party ad servers. This can lead to less robust


• Some mobile ad servers cannot accept tags where the creative is advertiser

ad server hosted, and therefore the creative must be sent with a 1x1

impressions and click tracking tag.

• Third party ad servers can sometimes not be fully compatible with 100% of

publishers SDK’s. To ensure this doesn’t affect the ad serving process thorough

testing should be carried out between the ad servers and SSP’s (Sale Side

Platform) / publishers to make sure the ads are rendering correctly.


Can you use third party ad-serve for HTML 5 ad units?

• Yes, this is entirely possible but is dependent on the ad server being used, and

if the publisher accepts it.

Is there a difference between rich media and standard ad serving on mobile?

• It is often reported that rich media ad serving leads to higher discrepancies.

This is due to the higher complexity of rich media code, and often higher load

times. As mentioned previously, agreeing terminology on the definition of the

impression between all parties, including the rich media supplier, before the

launch of a campaign will decrease the likelihood of confusion at the reporting


• Apple devices can’t display flash – This means that if a campaign is set up to

deliver a flash creative, a backup GIF or JPEG will be served instead. To explain

further, when a rich media campaign is set up, the creative agency will supply

the ad server with a number of different ad formats to accommodate for the

different devices in the market place. Because Apple devices cannot display

flash, a more basic format is pushed through – in the form of GIF or JPEG

developed for the desktop creative. When an Apple device is detected by an ad

server this format will, in theory, be served to ensure the ad unit displays to the


What is the difference between an install and a download?

There are two trains of thought with regards to this question:

1. An install represents the full installation of an app on a device. While most

apps install quickly once downloaded, there are typically several seconds

between the start of the download of an app and its installation. It is the start

of the download (not its completion) that is easiest to track, and therefore if the

chain breaks i.e. the app is downloaded but doesn’t install, a discrepancy will


2. A download is when the user has downloaded the app from an app store.

The install is only completed and counted when they open the app for the first


Ask the question before a campaign goes live. What are you counting as an

install and download? This will ensure all parties involved are counting the same



Section Two - Connection

Why are IP addresses not as reliable on mobile?

Mobile operators differ in how they handle IP address allocation. Some

operators have a fixed IP address for all of their users, others dynamically

allocate IP addresses each time the device connects.

• Most mobiles, whether on 3G or wifi, will connect via a NAT-ed connection.

This means many different handsets will appear to be coming from the same IP


• Where the data connection is using a mobile network operator (MNO)

gateway, the IP address will be the IP address of the MNO gateway, which will

handle multiple user sessions.

• The handover from one mobile phone tower to the next can result in IP

changes, and thus tracking these changes can be problematic.

• Dropping from 3G to 2G connection has an effect on the reliability of an IP


What happens when a user doesn’t have a data connection?

• Dependent on publishers SDK’s, sometimes no ad will be displayed,

sometimes an ad cached from a previous session may be shown to the user.

However, the user will have no way of interacting with the ad.

• The only exception is rich media where the ad experience can be totally

loaded before a user has clicked the banner. Either way, no data (such as

engagement information) can be passed back to a server without a connection

unless the information is stored by the device until a connection returns.

• Some apps are built for offline experience. In those cases when the latest

version is downloaded the ad creative (all assets) are downloaded as well. While

there is no “click to landing page” experience, other engagement can be

recorded and set to the publisher next time the device is connected.


How is location determined on a mobile device?

There are a number of ways in which technology can be used to track a

consumer’s location. Below are the three traditional methods which are currently

available and commonly used for Location Based Advertising.

• Network-based. This technique utilises the service providers’ (mobile network

operators MNOs) infrastructure to identify the location of a handset. This method

is generally used by MNOs in a non-intrusive way without having to add any

software to the handset. Examples of companies using this technique are O2

and Orange.

• Handset-based. This technique requires the installation of software on the

handset to determine its location. The location is found by computing the

handset’s cell identification. In addition, if the handset is also equipped with

Global Positioning System (GPS) then significantly more precise location

information can then be sent from the handset.

• Hybrid. This technique uses a combination of network-based and

handset-based technologies to identify the location. One example would be

some modes of Assisted GPS, which can both use GPS and network information

to determine the location. Both types of data are used by the mobile phone to

identify the location faster and more accurately.

Note - Just because the device knows where it is to a given precision, it doesn’t

necessarily follow that this will be passed on to a third party.


Section Three - Tracking

Do you need mobile specific tags for tracking?

• Preferred, but not mandatory. Simple tags in theory work relatively well to

produce relevant advertising on mobile browsers – except on some browsers,

where third party cookies are blocked by default.

• In app advertising, on the other hand, relies on an SDK and will usually have

code specific to that SDK. As a result, mobile and tablet devices should have their

own specific tags.

What are the differences between app and browser ecosystems for tracking?

Mobile browsing relies on cookies, whilst in-app identification is more diverse.

Behavioural advertising on mobile is much more complex than desktop web,

where cookies are the main targeting mechanism. Several browsers commonly

used on mobile devices block third party cookies by default, making it difficult

to provide behavioural advertising using this technology. Even when third party

cookies are not disabled, these cannot be accessed from mobile apps, where

other forms of identification (such as fingerprinting or Unique Device Identifiers)

are needed.

What targeting mechanisms can be used across mobile apps?

There are different options available and often a combination is needed.

Mechanisms that can be technically used to identify users across mobile apps


• Device Parameters such as the Apple Identifier for Advertisers (IDfA), MAC

addresses and other type of unique device IDs.

• First Party Cookies / HTML5 Cookies, these can work but they interrupt the

user journey by temporarily redirecting users to the mobile browser.

• Probabilistic Device Recognition (e.g. fingerprinting), this is based on the

collection of multiple data points (such as location, timestamp, device name,

make, model, browser, etc) to generate a virtual identity or probabilistic device

ID. This technology is based on probabilities and therefore not 100% accurate,

however, it can be used across both mobile web and app environments.


Another option is to develop a hybrid identifier, which essentially is a mixture

of two or more of the mechanisms mentioned . This is very commonly used as

multiple touch points help to improve the accuracy.

Do cookies demonstrate the same behaviour on mobile browsing as they do on


• No, there are key differences in mobile browsers’ default settings, which few

users change. Many mobile devices are strict about serving third-party cookies.

For example, Safari blocks third party cookies by default, cookies dropped on

an impression are generally always third party and would be blocked on Safari.

Firefox’s new proposed default cookie settings are similar but slightly different, as

third party cookies will be blocked unless the user has ever gone to that domain

in a first party context.


If you are using fingerprinting and other mechanisms to deliver relevant

advertising, what privacy concerns should you be aware of?

The privacy considerations are specific to each type of identifier.

1. Probabilistic device recognition (including fingerprinting) relies on

probabilities and statistical matches rather than bits of code. Unless the user is

given an explicit ability to opt out of this form of data collection for targeting, it is

recommended to expire the fingerprint after a period time (e.g. 30-60 days).

2. Cookies on mobile browsers, like on the static web, are bits of code that are

dropped on a user’s device. If using cookies, we recommend that you sign up to

the EU self-regulatory framework for Online Behavioural Advertising (OBA) to give

users an opportunity to opt-out of behavioural targeting.

3. Unique Device Identifiers (UDIs) provide 100% accuracy on the device

identity, and their use is broadly moderated by the platform owners. However,

third parties working with apps should take care to incorporate additional

privacy safeguards. It is recommended that you require first party app

developers to provide a privacy policy that discloses what data is collected, by

whom and how; as well as what controls the user has over the collection and

use of their data by third parties.

Are there any mechanisms to detect fraudulent clicks?

• There are a number of technologies used, many coming from online.

The same mechanisms that are used to detect fraudulent clicks on non-mobile

display (removing known bot traffic, blocking certain IP addresses, etc.) are also

in place for mobile. Some of these are simple solutions (such as not counting

repeated clicks from a particular IP address) and others are more complex,

relying on mechanisms that would dynamically identify sources of fraudulent

clicks, for example, through an analysis based on heuristics including device ID,

user agent and timing. Overall, the main issue is the lack of

standardization - what is and isn’t in use can vary a lot between suppliers and

technology providers.



Third Party Ad serving - The technology used to deliver creative assets from one

ad server into another, allowing advertisers to track the performance of the

campaigns and recording impressions and clicks amongst other campaign


Ad server - A computer that delivers and tracks advertisements independent of

the web site where the ad is being displayed. Use of an ad server helps

establish trust between an advertiser and publisher since the statistics can be

maintained by an objective third party.

Who uses: Advertisers, Agencies, DSPs, Ad Networks, Publishers.

Behavioural Advertising - A form of digital marketing where segmentation is

produced on the basis of previous decision making behaviour (e.g. filling out

preferences or visiting certain areas of a site frequently).

Cookies - Bits of code placed on a user’s browser by a web server that can be

stored or retrieved when the site is accessed.

Fingerprinting - A virtual profile generated by assembling several pieces of

information, often used to track generic patterns of behaviour.

GIF - A compressed image file format. These compressed image files can be

quickly transmitted over a network or the internet, which is why you often see

them on web pages. GIF files are great for small icons and animated images,

but they lack the colour range to be used for high-quality images.

HTML5 - A new standard for displaying content on the web through browsers.

HTML5 is the new rendition in work of HTML (hypertext markup language) that

will be competing directly with Flash and includes features like video playback

and drag-and-drop functionality.


Hybrid identifier - A combination of two or more digital marketing mechanisms.

JPEG - A compressed image file format. JPEG images are not limited to a certain

amount of colour, like GIF images are. Therefore, the JPEG format is best for

compressing photographic images.

NAT-ed - NAT is Network Address Translation, which allows hundreds, or even

thousands, of devices to share the same external IP address behind a firewall

gateway. The device has a local IP address which is translated to a single public

one as traffic passes through the gateway.

Real time bidding (RTB) - RTB is a protocol that enables the valuation and bidding

on individual impressions in real time. The buying takes place over online media

exchanges – basically media marketplaces – which connect sellers (publishers)

and buyers (advertisers).

Sale Side Platform (SSP) - A technology platform with the single mission of

enabling publishers to manage their ad impression inventory and maximise

revenue from digital media. As such they offer an efficient, automated and

secure way to tap into the different sources of advertising income that are

available, and provide insight into the various revenue streams and audiences.

Server - A host computer which maintains websites, newsgroups and email


Software Development Kit (SDK) - Usually platforms provide developers with a set

of development toolkits that enable creation of software packages, frameworks,

apps etc. There is usually an SDK for each language that works on the platform

that interfaces between the system to the programming language.

Tags - An ad tag is a piece of HTML or JavaScript code that your webmaster or

developer inserts into the source code of a web page. You need to create a

separate ad tag for each ad that you want to display on your website.

Unique Device Identifiers (UDI) - Serial numbers associated to each mobile

device or to one of its components.


With thanks to everyone who contributed...


Intelligent targeting



Published May 2013

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